Matthew 13:2

And great multitudes were gathered unto him
Some on one account, and some on another; some to see his person, others his miracles; some healing for their bodies, and others for their souls; some for the loaves, and others to hear him preach; and of these there were several sorts, as the following parable shows.

So that he went into a ship:
both for his own advantage, that he might not be crowded, and pressed by the people, and have more room, and a freer air to speak in, and for theirs, that they might both see and hear him better. And sat, and the whole multitude stood on the shore;
as was the then custom of the Jewish doctors and hearers, the one to sit, and the other to stand. (See Gill on Matthew 5:1). Christ sat upon the deck of the ship; or perhaps this ship was no other than an open boat, which was put to sea, some little distance from the shore; upon which the people stood in great numbers, with much convenience and attention.